Current interrupting safe break terminator

ABSTRACT

A current interrupting connector for connecting a high voltage shielded cable to underground distribution apparatus, the connector including a housing formed of resilient insulating material and having a connection recess for an electrically conductive element and a cable termination passage sealed at both ends for housing a removable non-expulsive or non-gas forming interrupter. Electrical connectors are provided in the passage for connecting the interrupter to the electrically conductive element and to the high voltage cable. Each of the connectors is molded into electrically conductive sleeves which also surround and electrically shield the interrupter.

United States Patent Link et al. [4 1 Aug. 2 2, 1972 CURRENTINTERRUPTING s 3,116,386 12/1963 Sperzel ..339/59 X BREAK TERNHNATOR3,134,874 5/1964 Cameron ..337/ 159 [72] Inventors: Edwin Link waukesha;Edward 2,246,193 6/1941 Smith, Jr. ..337/l9l y, New B n. h of W FOREIGNPATENTS OR APPLICATIONS Assigneol RTE rp Waukosha, i 828,861 2/1960Great Britain ..337/224 [22] 1969 Primary Examiner-Bemard A. Gilheany PP8 Assistant Examine rDewitt M. Morgan Attorney-Ronald E. Barry and JamesE. Nilles s21 u.s..c|. ..337/201, 337/224 51 int. Cl.....H0lh 85/02,H.0lh 85/22-,-HOlr 13/46 [57] ABSTRACT [5M Field of Search ..l74/73;337/191,:192, 193,- A cu n r p i g connector. o connecting 81 337/197'201.205, 2 3; 339 45 59 0, high voltage shielded cable to undergrounddistribu- 0 1 1 1 143 tron apparatus, the connector including a housingj I a formed of resilient insulating matenal and having a 5 ReferencesCi connection recess for an electrically conductive eler ment and acable ternunation passage sealed at both UNITED STATES PATENTS ends forhousing a removable non-expulsive or nongas forming interrupter.Electrical connectors are profi 'z vided in the passage for connectingthe interrupter to 2660644 11 1953 f 337 224 the electrically conductiveelement and to the high I urray 3 voltage cable. Each of the connectorsis molded into 2593426 4/1952 pahnpe 7/224 electrically conductivesleeves which also surround and electricallyshield the interrupter.

3,307,137 2/1967 7 Claims, 1 Drawing Figure Tordoff et ah. 1 74/73 XCURRENT INTERRUPTING SAFE BREAK TERMINATOR BACKGROUND OF THE INVENTIONUnderground distribution systems are rapidly replacing the conventionaloverhead distribution system. Due to the low inductance of undergroundcables, high fault currents can and do occur in these systems. Thesefault conductive stranding 38. The cable 12 is prepared for terminationby removing the stranding 38 and stripping SUMMARY omwvgmon ,ljl

c The invention described herein provides'a current interruptingconnector for interrupting hi'gh fault cur f rents which is adaptable to.anundergrounddisti'ibution I system. This connector incorporates thefeatures of a safe break terminator of the type shown in-applicationSer. No. 748,142. The connector includes an insulating housing in theform of a termination elbow used in the off the semiconductive sheath 36to expose a portion of the cable insulation 34. The cable insulation 34is cut away to expose a predetermined length of the conductor 32. Aterminal lug 40 having an axially extending opening 42 at one end issecured to cable 12 by inserting the exposed conductor 32 into theopening 42 and crimping the lug at 44 to secure the lug to the conductor32. A threaded aperture 46 is provided at the other end of the lug 40.

ln'accordance with the invention, the current interrupting connector 10includes a housing 50 in the form of an elbow formed from a resilientinsulating material such as clay filled, ethylene propylene terpolymeravailable under Du Ponts trademark Nordel and has a connection recess 52and a cable termination passage 54, having a reduced diametersection 55.The connection recess 52 is tapered for mating engagement with the outersurface 24 of the housing 22'of the bushing to form a seal onconnection. An electrically conductive element 56 having a threadedportion'57'is positioned in the recess 52 for telescopic engagement withthe electrically conductive sleeve 30. An insulating member 58 of arcextinguishing material is provided on the end of the conductive element56 which cooperates with the insulating member 28 in the connectioninlet current magnitude,'various interrupters could be employed such asa sand fuse, oil fuse cutout or a vacuum interrupter. The housing isprovided with a termination passage with electrical connectors mountedin a spaced relation in the passage to electrically engage theinterrupter. One of the connectors is connected to an electricallyconductive element which is adapted to be connected to a bushing fortheterminator. The other connector is connected to the high voltage cable.

Other objects and advantages of the present invention will becomeapparent from the following description when read in connection with theaccompanying drawing, in which an elevational view is shown of thecurrent interrupting connector mounted on the bushing for a transformer.

DESCRIPTION OF THE INVENTION I other specific structure.

The current interrupting connector 10 of this invention is used tointerruptfault currents at the electrical connection of a high voltagecable 12 to a bushing 14 provided on a wall of an undergrounddistribution transformer. The bushing 14 forms one part of an electricalconnector of the type shown in application Ser. No. 748,142 and includesa housing 22 formed of electrically insulating material having a taperedouter surface 24 and a connection inlet 26. An insulating member 28 ofarc extinguishing material is positioned within the connection inlet-26in coaxial alignment with an electrically conductive sleeve 30 which isconnected to electrical apparatus within the transformer.

The high voltage cable 12 includes an electrical conductor 32, eithersolid or stranded, a cable insulation 34, a semiconductive sheath 36,and an electrically 26 to extinguish the are on disconnection asdescribed in application Ser. No. 748.142.

Means are provided in the passage 54 for supporting the electricallyconductive element 56 in the recess 52. Such means includes anelectrically conductive ring 60 having on one side a break or split andon the other-side a boss 64 having a threaded aperture 66. The threadedportion 57 of the electrically conductive element 56 is threadedlyreceived in threaded aperture 66.

The ring 60 is supported in the passage 54 by means of a first innermember which is molded in the form a sleeve from a resilientelectrically conductive material such as an ethylene propyleneterpolymer available under Du Ponts trademark Nordel. The inner member70 includes a portion 72 which forms the inner end of the connectionrecess 52 and seals the connection recess 52 from the passage 54. Theinner member 70 also surrounds the boss 64 and provides an electricalshield around the ring 60 and along a portion of the inside of thepassage 54.

Cable termination is provided in the passage 54 by means of anelectrical-connector 74 having a threaded boss 76 which is threadedlyreceived in the threaded aperture 46 in the terminal lug 40. Theelectrical connector 74 has aflat base 77 and upwardly extending tangs78 which converge slightly toward the center of the passage 54.

The connector 74 is supported in the passage 54 by means of a secondinner member 80 molded in the form of a sleeve from a resilientelectrically conductive material. The second inner member 80 includes afirst portion 82 having an inside diameter slightly smaller than thediameter of terminal lug 40 to provide a tight fit on insertion of theterminal lug 40 into the elbow. A good electrical contact is therebyprovided between the terminal lug 40 and the innermember 80. Theremaining or second portion 84 of the inner member 80 ex: tends axiallyalong a portion of the passage 54 terminating short of the inner member70.

covers the inner surface of the second inner member 80.

Fault currents in the cable 12 are interrupted by means of anon-expulsive or non-gas forming interrupter 85 which is removablypositioned in the passage 54.'The interrupter 85 preferably comprises a.sand

vided within the tubular insulating body 86 which is completely filledwith sand 92. The interrupter 85 is a 4 means for interrupting currentremovably positioned in said passage,

first means for electrically connecting said current interrupting meansto said electrically conductive member and second means forelectricallyconnecting said current interrupting means to a high voltageshielded cable, a first inner member formed of an electricallyconductive material disposed within and extending axially along aportion of said passage to electrically shield one of said first meansand. said second means and the corresponding portion of said currentinterrupting means. I '2. The electrical connector'according to claim 1ineluding a second member formed of an electrically conductive materialdisposed within and extending 1 along a portion of said passage toelectrically shield the conventional type fuse and is capable ofinterrupting 1 fault currents above 10,000 amperes. Other types ofnon-expulsive interrupters can also be used depending upon the magnitudeof the contemplated fault current such as an oil fuse cutout or a vacuuminterrupter. a

The electrical circuit between the ring 60 and the electrical connector74 is completed by inserting the interrupter 85 into the passage 54until one of the caps 88 is seated against the base 77 of the connector74 and the other cap 88 is positioned in the split ring 60. In thisregard, the split ring 60 has an internal diameter slightly smaller thanthe outside diameter of the cap 88 to allow the fuse 85 to be-insertedthrough the split ring 60 into the passage 54. The inherent resiliencyof the I ring 60 will produce an electrical connection between the ring60 and the caps 88. The tangs 78 on the conductor 74 are bent inwardslightly to provide an inherent bias for electrically engaging the cap88 on the fuse 85.-

The cable termination passage 54 is sealed at the open end by means of acap 93 having a tapered inner surface 94 which matingly engages theouter surface of the housing. The other end of the passage 54' is sealedby means of the engagement of the section 55 with the cable insulation34. The internal diameter of the section55 is slightly smaller than theoutside diameter of the cable insulation 34.

The outer surface of the housing 50 is electrically shielded by coatingthe housing with an electrically conductive material 96. An electricallyconductive tape 98 is wound around the housing to connect theelectrically conductive material 96 to the conductive sheath 36 on thecable 12. The integrity of insulation from the apparatus to the cablewill be continuous when the connector 10 is mounted on the bushing 14. 7

Various of the features of the invention are set forth in the followingclaims:

What is claimed is:

1. An electrical connector for connecting a high volt- 'ment positionedwithin a bushing for an underground electrical apparatus, said connectorcomprising,

a housing formed from a resilient dielectric insulating material andhaving a passagetherein,

an electrically conductive member positioned in said housing and adaptedto be connected to the electrically conductive element in the bushing,

other of said first means and said'second means and the correspondingportion of said current interrupting means and means for electricallyinsulating saidfirst inner member from said second inner member.

3. An electrical connector for connecting a high voltage shieldedcableto an electrically conductive element positioned within a bushing for anunderground electrical apparatus, the bushingincluding an arcextinguishing member at the entry end of the conductive element, saidconnector comprising a housing formed from a resilient dielectricinsulating material and having a recess which is adapted to sealinglyengage the bushing,

an electrically conductive member positioned in said housing and adaptedto be connected to the electrically conductive element in the bushing,

an insulating member of arc extinguishing material on the end of saidelectrically conductive member,

means for interrupting current removably positioned in said housing,

first means for electrically connecting said current interrupting meansto said electrically conductive member,

said second means for electrically connecting said current interruptingmeans to -the high voltage shielded cable, a t

a first inner member formed of an electrically conductive materialdisposed between said first means and said housing to electricallyshield a first portion of said current interrupting means,

and a second member formed of an electrically conductive materialdisposed between said second means and said housing to electricallyshield a second portion of said current interrupting means.

4. A connector according to claim 1 wherein said current interruptingmeans comprises a sand filled fuse having an insulating housing, anelectrically conductive cap at each end of said housing,

a fuse link within said housing electrically connected to said caps,

and sand completely filling said housing.

5. A current limiting unit according to claim 4 6. A current limitingunit according to claim 4 wherein said second electrically connectingmeans comprises a base having a number of inwardly disposed tangs toengage one of said caps.

7. An electrical connector for connecting a high voltage cable to areceptacle having an electrically conductive sleeve connected to a highvoltage conductor, and an insulating sleeve or arc extinguishingmaterial at the entry end of the electrically conductive sleeve, saidconnector comprising,

an insulating housing having a connection recess adapted to matinglyengage said receptacle and a cable termination passage, said housingbeing formed from a resilient insulating material,

a pair of electrically conductive connectors supported in a spacedrelation in said passage,

an electrically conductive element positioned in said a recess forinsertion into the electrically conductive ductive material disposedbetween one' of said pair of electrically conductive connectors and saidinsulating housing to electrically shield a portion of said currentinterrupting means,

and a second inner member formed of an electrically conductive materialdisposed between the other of said pair of electrically conductiveconnectors and said insulating housing to electrically shield the otherportion of said current'interrupting means.

1. An electrical connector for connecting a high voltage shielded cableto an electrically conductive element positioned within a bushing for anunderground electrical apparatus, said connector comprising, a housingformed from a resilient dielectric insulating material and having apassage therein, an electrically conductive member positioned in saidhousing and adapted to be connected to the electrically conductiveelement in the bushing, means for interrupting current removablypositioned in said passage, first means for electrically connecting saidcurrent interrupting means to said electrically conductive member andsecond means for electrically connecting said current interrupting meansto a high voltage shielded cable, a first inner member formed of anelectrically conductive material disposed within and extending axiallyalong a portion of said passagE to electrically shield one of said firstmeans and said second means and the corresponding portion of saidcurrent interrupting means.
 2. The electrical connector according toclaim 1 including a second member formed of an electrically conductivematerial disposed within and extending along a portion of said passageto electrically shield the other of said first means and said secondmeans and the corresponding portion of said current interrupting meansand means for electrically insulating said first inner member from saidsecond inner member.
 3. An electrical connector for connecting a highvoltage shielded cable to an electrically conductive element positionedwithin a bushing for an underground electrical apparatus, the bushingincluding an arc extinguishing member at the entry end of the conductiveelement, said connector comprising a housing formed from a resilientdielectric insulating material and having a recess which is adapted tosealingly engage the bushing, an electrically conductive memberpositioned in said housing and adapted to be connected to theelectrically conductive element in the bushing, an insulating member ofarc extinguishing material on the end of said electrically conductivemember, means for interrupting current removably positioned in saidhousing, first means for electrically connecting said currentinterrupting means to said electrically conductive member, said secondmeans for electrically connecting said current interrupting means to thehigh voltage shielded cable, a first inner member formed of anelectrically conductive material disposed between said first means andsaid housing to electrically shield a first portion of said currentinterrupting means, and a second member formed of an electricallyconductive material disposed between said second means and said housingto electrically shield a second portion of said current interruptingmeans.
 4. A connector according to claim 1 wherein said currentinterrupting means comprises a sand filled fuse having an insulatinghousing, an electrically conductive cap at each end of said housing, afuse link within said housing electrically connected to said caps, andsand completely filling said housing.
 5. A current limiting unitaccording to claim 4 wherein said first electrically connecting meanscomprises a split ring having an internal diameter slightly smaller thanthe outside diameter of said caps and a boss integral with said ring forsupporting said electrically conductive member.
 6. A current limitingunit according to claim 4 wherein said second electrically connectingmeans comprises a base having a number of inwardly disposed tangs toengage one of said caps.
 7. An electrical connector for connecting ahigh voltage cable to a receptacle having an electrically conductivesleeve connected to a high voltage conductor, and an insulating sleeveof arc extinguishing material at the entry end of the electricallyconductive sleeve, said connector comprising, an insulating housinghaving a connection recess adapted to matingly engage said receptacleand a cable termination passage, said housing being formed from aresilient insulating material, a pair of electrically conductiveconnectors supported in a spaced relation in said passage, anelectrically conductive element positioned in said recess for insertioninto the electrically conductive sleeve and secured to one of saidconnectors, an insulating member of arc extinguishing material on theend of said element, means for terminating a cable secured to the otherof said connectors, means for interrupting fault currents removablypositioned in said passage in electrical contact with said connectors,means for sealing said passage, a first inner member formed of anelectrically conductive material disposed between one of said pair ofelectrically conductive connectors and said insulating housing toelectrically shield a portiOn of said current interrupting means, and asecond inner member formed of an electrically conductive materialdisposed between the other of said pair of electrically conductiveconnectors and said insulating housing to electrically shield the otherportion of said current interrupting means.